Over 1 billion persons worldwide have iron deficiency anemia (IDA). In the United States, an estimated 3% of young children (age 1 to 4 years) have IDA, a time of rapid growth during which iron is critical for development. Oral iron has been used for centuries for primary treatment, however, non-adherence results in treatment failure in a substantial number of patients. Two promising alternative approaches exist to oral iron: (1) optimization of oral iron delivery via a behavioral adherence intervention, and (2) directly observed therapy (DOT) of a one-time infusion of intravenous (IV) iron. Should either regimen demonstrate improved outcomes, the result would lead to a paradigm shift in the treatment of patients with IDA. This proposal describes a career development plan that will prepare the candidate to become a successful independent investigator and attain her long-term career goal of becoming an international leader in the management of patients with IDA. The PI's immediate goal is to identify the most effective approach for successful treatment of children with iron deficiency anemia (IDA). To meet this goal, she has proposed a career development plan that integrates didactic coursework, participation in local and national conferences and intensive workshops, and mentored research studies within the distinguished and collaborative research environment at UT Southwestern in Dallas, Texas. This environment includes an NIH-funded CTSA within the Center for Translational Medicine and an AHRQ-funded Center for Patient-Centered Outcomes Research. The research aims of this project are to: 1) determine rates of oral iron medication adherence and characterize barriers to and facilitators of iron therapy in young children with nutritional IDA; 2) develop an adherence intervention for caregivers of children with IDA; and 3) pilot the intervention against standard oral iron and a DOT regimen with a one-time dose of IV iron. These aims will serve as the foundation for the PI's career development plan and training aims: 1) qualitative research methods; 2) intervention development; and 3) comparative effectiveness research. Together, the research and training aims of this K23 proposal will provide the training, experience, and preliminary data for an R01 application for an RCT sufficiently powered to compare the clinical efficacy of the optimized oral iron regimen with standard oral iron and the DOT regimen of IV iron. Outcomes examined will include clinical impact as well as patient-centered outcomes such as health-related quality of life. The proposed research and training aims will allow the PI to develop expertise in mixed-methods, intervention development and comparative effectiveness research while becoming a leader in the management of IDA. The innovative approach of assessing a novel adherence intervention against usual care with oral iron as well as the alternative of IV iron therapy challenges the paradigm of oral iron therapy for children with IDA. It has the potential for high impact on clinical care in children with IDA.